For both work and pleasure, these 20 social networking sites are the most useful to any busy IT professionals.

Don't have enough time to go looking for news and information or even to e-mail friends and colleagues? If so, then try using social networks. We've selected 20 of the most useful social networks for IT professionals. And these networks aren't just for work, either; some of them will help you find old friends and colleagues, keep in touch with family and friends, and get useful news and information for your busy professional life.

Digg
is the largest and most popular social news Web site on the Internet. Covering all topics including; politics, entertainment, technology and general news. Includes a separate video and image section. Allows users to share articles with their friends list or post to the most popular blog sites directly on a topic through Digg.

Mixx
is one of the newest in general social news sites which has a category for all types of news. Topics covered include business, entertainment, sports, health and tech. Also includes
personalization
with the ability to create groups to share news with other interested users.

StumbleUpon
is a social network and browser toolbar which allows users to channel surf the Internet. Technically not 100% a social news site, although users can submit Web pages to be rated by other users. Here is a
guide
to StumbleUpon.

Del.icio.us
is a social bookmarking site, which invites users to organize and publicize interesting items through tagging and networking. Is a great site for documenting your favorite bookmarks and sharing them with others. Each time a site is bookmarked is "voted on" and begins to rank higher in the search ranks of the site.

Technorati
is a network of blogs and writers that lists top stories in categories like Business, Entertainment and Technology. With so many blogs out there Technorati makes it easier for users to see the blogs they want without having to go to so many sites.

LinkedIn
is a popular networking site where alumni, business associates, recent graduates and other professionals connect online. Users can utilize the network to find old colleagues, gather references, post their resume and network for career opportunities.

Facebook
is no longer just for college kids who want to post their party pics. Businesses vie for advertising opportunities, event promotion and more on this site. Users are beginning to create groups for everything from alumni associations to bird watching.

Networking For Professionals
is another online community that combines social and business networking on the Internet with special events in the real world. Post photos, videos, résumés and clips on your online profile while you meet new business contacts

Everyone's heard of
YouTube
, the single largest video streaming site on the internet. But anyone can have their own channel for videos at YouTube. Create an account and upload a behind-the-scenes video from your company's latest commercial or event to give customers and clients an idea of what you do each day.

SecondLife
is a 3-D virtual world that is so popular it makes money by selling virtual real-estate for hard cash. Several major companies have set up shop in SecondLife and Reuters has opened a news bureau there.

MySpace
is a self-publishing within your network of friends and colleagues. It's a grapevine. It aggregates opinion (what to listen to, what to watch, what's groovy) and is now the most popular web site in the United States.

Livejournal
is part self-publishing network and part blog; but has added security, privacy and filtering abilities that other social networks are lacking, making it ideal for those who wish to utilize a single account for multiple audiences. It is one of the fastest growing and most diverse social networks of its kind

Dzone
is a free link-sharing community for developers. Members
vote on upcoming links
to determine what gets promoted. While everyone can browse, search and comment on links. Other topics commonly featured include web design and programming.